1. Field of the Invention
The present invention relates to an inkjet printhead. More particularly, the present invention relates to a piezoelectric inkjet printhead capable of reducing a crosstalk and a method of manufacturing the same.
2. Description of the Related Art
An inkjet printhead is a device for ejecting fine ink droplets for use in printing. For example, it is used to print at a desired point on a paper and to print an image of a predetermined color. Inkjet printheads can be generally divided into two types according to the type of ink ejection employed. One type is a thermally-driven inkjet printhead that creates a bubble in ink using a heat source, to thereby eject the ink using the expansion force of the bubble. The other type is a piezoelectric inkjet printhead that uses a piezoelectric element to eject ink using a pressure applied to the ink, which is generated by deformation of the piezoelectric element.
The construction of a typical piezoelectric inkjet printhead is illustrated in FIG. 1. Referring to FIG. 1, a manifold 2, a restrictor 3, a pressure chamber 4 and a nozzle 5, which together constitute an ink channel, are formed in the inside of a channel plate 1. A piezoelectric actuator 6 is disposed on the channel plate 1. The manifold 2 is a path through which ink flowing from an ink reservoir (not shown) is supplied to one or more pressure chambers 4. The restrictor 3 is a path through which the ink flows from the manifold 2 to the pressure chamber 4. The pressure chamber 4 is a space filled with ink to be ejected. A pressure change, for ejection or refill of ink, is generated in the pressure chamber 4 by changing its volume by driving the piezoelectric actuator 6. The piezoelectric actuator 6 may deform an upper wall of the pressure chamber 4, which may serve as a vibration plate 1a. 
In operation, when the piezoelectric actuator 6 is driven to inwardly deform the vibration plate 1a, the volume of the pressure chamber 4 is reduced, resulting in a pressure change. Ink in the inside of the pressure chamber 4 is ejected to the outside through the nozzle 5 by the pressure change in the inside of the pressure chamber 4. Subsequently, when the piezoelectric actuator 6 is driven to outwardly deform and restore the vibration plate 1a to its original shape, the volume of the pressure chamber 4 increases, resulting in a second pressure change. The second pressure change causes ink to flow into the the pressure chamber 4 from the manifold 2 through the restrictor 3 due to the increased volume.
A conventional piezoelectric inkjet printhead is illustrated in FIG. 2. Referring to FIG. 2, the conventional piezoelectric inkjet printhead is formed by stacking and bonding thin plates 11 through 16. In particular, a first plate 11, having nozzles 11a for ejecting ink, is disposed at the lowermost side of the printhead, a second plate 12, having a manifold 12a and ink outlets 12b, is stacked thereon and a third plate 13, having ink inlets 13a and ink outlets 13b, is stacked on the second plate 12. The third plate 13 has an ink introducing port 17 for introducing ink to the manifold 12a from an ink reservoir (not shown). A fourth plate 14, having ink inlets 14a and ink outlets 14b, is stacked on the third plate 13 and a fifth plate 15 having pressure chambers 15a, the ends of which communicate with the ink inlets 14a and the ink outlets 14b, respectively, is stacked on the fourth plate 14. The ink inlets 13a and 14a serve as paths through which ink flows from the manifold 12a to the pressure chambers 15a, and the ink outlets 12b, 13b, and 14b serve as paths through which ink is discharged from the pressure chambers 15a to the nozzles 11a. A sixth plate 16 closing the upper portion of the pressure chambers 15a is stacked on the fifth plate 15, and drive electrodes 20 and piezoelectric films 21 serving as piezoelectric actuators are formed on the sixth plate 16. Thus, the sixth plate 16 serves as a vibration plate that is vibrated by the piezoelectric actuator and changes the volume of the pressure chamber 15a disposed beneath it using warp-deformation of the sixth plate 16.
FIG. 3 illustrates a view of another example of a piezoelectric inkjet printhead and FIG. 4 illustrates a vertical sectional view of the same. The inkjet printhead illustrated in FIGS. 3 and 4 may have a structure in which three silicon substrates 30, 40 and 50 are stacked and bonded. Pressure chambers 32 of a predetermined depth may be formed on a backside of the upper substrate 30. An ink inlet port 31, connected to an ink reservoir (not shown), may pass through one side of the upper substrate 30. The pressure chambers 32 may be arranged in two columns, one on each side of the printhead, in a lengthwise direction of a manifold 41 formed on the intermediate substrate 40. Piezoelectric actuators 60, for providing driving force to eject ink to the pressure chambers 32, may be formed on an upper surface of the upper substrate 30. The intermediate substrate 40 may have the manifold 41, which may be connected with the ink inlet port 31 and restrictors 42. The restrictors 42 may be connected with the respective pressure chambers 32 formed on both sides of the manifold 41. Also, dampers 43 vertically passing through the intermediate substrate 40 may be formed on the intermediate substrate 40 in positions that correspond to the pressure chambers 32. Also, nozzles 51 connected with the dampers 43 may be formed in a lower substrate 50.
In operation, ink that has flowed into the manifold 41 through the ink inlet port 31 flows into the pressure chambers 32 by way of the restrictors 42. Subsequently, when the piezoelectric actuators 60 operate to pressurize the pressure chambers 32, the ink within the pressure chambers 32 passes through the dampers 43 and is ejected to the outside through the nozzles 51. Here, the restrictors 42 not only serve as paths supplying the ink from the manifold 41 to the pressure chambers 32 but may also prevent the ink from flowing backward to the manifold 41 from the pressure chambers 32 when the ink is ejected.
However, when the piezoelectric actuators 60 pressurize the pressure chambers 32, the pressure transferred to the pressure chambers 32 may also be transferred to the restrictors 42. Such a situation may generate crosstalk between adjacent restrictors 42. In this regard, crosstalk means mutual interference of pressures between adjacent restrictors 42, generated when ink is ejected. Crosstalk may affect the size of an ink droplet ejected from the nozzles 51, causing ink ejection to become non-uniform. That is, when crosstalk is generated, unintended ink may be ejected or an inaccurate amount of ink may be ejected, thus deteriorating print quality.